Printing apparatus

ABSTRACT

Printing methods and the apparatus therefor are provided in accordance with the teachings of the present invention. According to one embodiment of this invention a radiant energy source selectively transmits radiant energy through a plurality of character patterns arranged in columns and rows. The character patterns are adapted to move relative to the source so that radiation modulated by predetermined ones of the character patterns is selectively applied to a plurality of input paths of an optical positioning means. The optical positioning means includes optical tunnel means which acts to position radiation received at any of a plurality of input paths thereto to a single output location. Photoreceptor means is located at the output location of the optical positioning means whereupon modulated radiation applied to any of the input paths of the optical positioning means is communicated to and imaged upon such photoreceptor means. The photoreceptor means thereby receives modulated radiation corresponding to selected character patterns. The photoreceptor means may then be developed and the images present thereon transferred to print receiving means.

* Q C9 to XR 3 9 6 9 3 9 517 I 1 United mates ra i 3,693,517 Clark Sept.26, 1972 PRINTING APPARATUS vided in accordance with the teachings ofthe present 7 Inventor; Harold Clark, penfield, invention. According toone embodiment of this in- 73 A X vention a radiant energy sourceselectively transmits 1 emx Cowman! Rochester radiant energy through aplurality of character pat- [221 Filed; Dec. 23,1969 terns arranged incolumns and rows. The character 21 Appl. No.: 887,666

[52] US. Cl ..95/4.5 [51] int. Cl. ..B41b 21/24 [58] Field of Search..95/4.5; 340/378 [56] References Cited UNITED STATES PATENTS 3,26l,2847/1966 Lynott ..l01/114 2,887,935 5/1959 Scott 3,204,540 9/1965 Blakely3,252,392 5/1966 Ward ..95/4.5

Primary Examiner-John M. Horan Attorney-James J. Ralabate, David C.Petre, Michael H. Shanahan and Marn & .langarathis [57] ABSTRACTPrinting methods and the apparatus therefor are propatterns are adaptedto move relative to the source so that radiation modulated bypredetermined ones of the character patterns is selectively applied to aplurality of input paths of an optical positioning means. The opticalpositioning means includes optical tunnel means which acts to positionradiation received at any of a plurality of input paths thereto to asingle output location. Photoreceptor means is located at the outputlocation of the optical positioning means whereupon modulated radiationapplied to any of the input paths of the optical positioning means iscommunicated to and imaged upon such photoreceptor means. Thephotoreceptor means thereby receives modulated radiation correspondingto selected character patterns. The

1 photoreceptor-means may then be developed and the images presentthereon transferred to print receiving means.

5 Claims, 2 Drawing Figures High Voltage v PRINTING APPARATUS Thisinvention relates to printing methods and the apparatus therefor and, inparticular, to methods and apparatus for producing printed documents inresponse to received data signals.

In the printing arts, the two major categories of printing apparatusthat have been developed may be classified as impact printers andphotoprinters. Conventional impact printers require hammer means tostrike a selected character embodied in a character matrix, whichselected character is forced into contact with a recording medium,thereby printing a character. Impact printing techniques are exemplifiedby slow speed, shock and vibration caused by hammer movement, andexcessive wear on the mechanical components.

Conventional photoprinter systems act to record images of typecomposition on a photosensitive medium by the utilization of flashinglight emissive elements which image character patterns, physicallydisposed between the light emissive elements and the photosensitivemedium, onto the medium through an optical path including high qualityfocusing means. Each character pattern may be a member of a font of typein stencil form mounted on a carrier. The carrier may be a rotating drumor disk. As the carrier rotates, each character pattern successivelypasses between the light emissive elements and the photosensitivemedium. If the carrier is a drum, the light emissive elements may beplaced within the drum in a stationary position and flashed by a controldevice as the desired character pattern passes before it. The controldevice may be a conventional typewriter keyboard, recording tape, punchcard, etc. After each character pattern is recorded on a photosensitivemedium, such as a galley film, the medium is advanced onecharacterwidth, resulting in a linear photographic record of the typecomposition. The font may be mounted on the carrier on a single strip,such as a single circumferential strip for a drum, or a single radialstrip for a disk. This results in a large circumference and requires ahigh speed of rotation of the carrier for efficient photoprinting. Thehigh rotation speed presents problems in synchronizing the flashinglight emissive elements to the movement of the photosensitive medium androtation of the carrier. Those skilled in the prior art have found thatthe rotational velocity of the carrier may be reduced without affectingthe efiiciency of photoprinting by mounting the font on the carrier as aplurality of strips at spaced lateral positions on the circumference ofa drum, or at discrete radial positions on a disk.

The location of the character patterns on different strips mounted onthe carrier requires a proper positioning between the photosensitivemedium, the optical focusing means, the light emissive elements, and thecharacter patterns themselves, in order to obtain proper alignment ofthe recorded character patterns. Some prior art devices employ fixedoptical focusing means, a fixed photosensitive medium and a single fixedlight emissive element. The font is mounted on a plurality of parallelcircumferential strips affixed to a surface of a drum, and the drum islaterally displaced in a direction parallel to its central axis so as toplace the proper character pattern on the corresponding circumferentialstrip into the correct position with respect to the light emissiveelement and optical focusing means.

Other prior art devices employ a plurality of light emissive. elements,one for each circumferential strip, and a single fixed optical focusingmeans. The drum is laterally shifted to place the appropriatefont-carrying strip and associated light emissive element into thecorrect position with respect to the optical focusing means. Still otherprior art devices employ a plurality of light emissive elementsassociated with each strip and displace the optical focusing means intothe proper position for imaging a selected character pattern onto thephotosensitive medium which is also displaced. The above describedconventional photoprinting devices suffer from the common disadvantageof requiring a highly complex and expensive mechanical device foreffecting displacement of the carrier, optical focusing.

means and photosensitive medium. In addition, the reliance upon aplurality of mechanical alignment devices to achieve a desired opticalpath results in high failure rates and requires stringent maintenance.

The aforementioned photoprinting systems record character patterns on aphotosensitive medium that is formed into a strip whose width is equalto the height of the largest character patterns. The character patternsare recorded serially and one character pattern is generally recordedfor every rotation of the carrier. Other conventional high speedphotoprinting devices record character patterns on a photosensitivemedium formed into a strip whose width is equal to the width of aprinted page. The character patterns are recorded by these conventionaldevices a line at a time and an entire line of character patterns isrecorded for every rotation of the carrier. Thus, if it is assumed thatthere are character patterns per line, the carrier may be a drum uponwhich are mounted 80 identical circumferential strips, each stripcontaining a complete character font. Behind each such character font,and included within the drum, is a light emissive element that isenergized when the proper character pattern is brought into alignmenttherewith as the drum rotates. A separate optical focusing means ispositioned between each strip mounted on the drum and the photosensitivemedium. As each line of character patterns passes between the lightemissive elements and the optical focusing means, selected ones of thelight emissive elements are energized when the character pattern alignedin the optical path constitutes the character pattern desired to beimaged upon the photosensitive element. For example, if a row of theletter e" is rotated into position, light emissive elements will beenergized whose positions correspond to those where an e is to appear onthat line. Although these prior art devices result in accurate, highspeed photoprinting, an attendant disadvantage therewith is that theline to be photoprinted must have previously been established, that is,character pattern information for the entire line must first be storedand then read out to flash the appropriate light emissive elements. Theline cannot be recorded as it is being composed; it must be in its finalform before it is recorded.

Therefore, it is an object of the present invention to provide highspeed printing methods and the apparatus therefor.

It is another object of this invention to provide high speed printingmethods and the apparatus therefor wherein radiant energy is employed toserially record character patterns on electrophotographic photoreceptormeans.

,It is a further object of the present invention to provide methods ofand the apparatus for printing at high speeds wherein the density ofcharacter patterns on a movable carrier is substantially increased.

It is yet another object of this invention to provide high speedprinting methods and the apparatus therefor wherein patterns of radiantenergy received at a plurality of points are optically communicated to apredetermined location by optical tunnel positioning means.

It is a still further object of this invention to provide high speedprinting methods and the apparatus therefor wherein a plurality oflaterally displaced character patterns on a rotating carrier may beselectively imaged upon a predetermined portion of a photoreceptorwithout any alteration of the optical path or lateral displacement ofthe rotating carrier.

It is an additional object of the present invention to provide methodsof and the apparatus for printing at high speeds while obtaining areduced velocity of a rotating carrier.

Various other objects and advantages of the invention will become clearfrom the following detailed description of an embodiment thereof, andthe novel features will be particularly pointed out in connection withthe appended claims.

In accordance with this invention high speed printing methods and theapparatus therefor are provided wherein an array of character patternsis moved relative to a source of radiant energy such that when thesource is selectively actuated, radiant energy is applied through aselected character pattern, modulated thereby and such modulated radiantenergy is further communicated to one of several input paths of anoptical tunnel means; the optical tunnel means acts to image radiationreceived at any of the input paths thereto at a singular predeterminedoutput location thereof; photoreceptive means are positioned at suchpredetermined output location whereby the radiation received thereat maybe developed and transferred to print receiving means.

The invention will be more clearly understood by reference to thefollowing detailed description of an embodiment thereof in conjunctionwith the accompanying drawings in which:

FIG. 1 is a perspective view of one embodiment of the imaging portion ofthe printing apparatus according to this invention; and

FIG. 2 shows an embodiment of printing apparatus according to thepresent invention adapted to illustrate the inventive methods set forthherein.

Referring now to the drawings, and more particularly to FIG. 1, there isshown the imaging portion of the printing apparatus, according to thepresent invention, for use in high speed printing comprising carriermeans 1, a source of radiant energy 13 and optical positioning means 7.Carrier means 1 is adapted to have mounted thereon or otherwise receivea plurality of character patterns in the form of strips or similarpresentations of character patterns such as the character patterns of anentire character font, and to move the character patterns relative toradiant energy source 13. In the embodiment of the invention illustratedin FIG. 1, carrier means I is shown as a rotatable drum; however, aswill be apparent to those of ordinary skill in the art, the carriermeans 1 may also take the form of a disk, an endless belt, or othercharacter-transport means capable of receiving a plurality of characterpatterns. The character patterns carried by carrier means 1 may bearranged in an array of rows and columns and may comprise the individualcharacters of an entire character font. The characters may be etchedonto the surface of carrier means 1, or, as shown in FIG. 1, may beformed of a plurality of strips, 111-115 wherein each strip comprises acolumn of character patterns, and the columns are aligned such that aplurality of rows of character patterns appears about the surface ofcarrier means 1. In the embodiment of the invention illustrated in FIG.1, five strips 111-115, each bearing a separate portion of an entirecharacter font, are mounted on the circumference of carrier means 1, andthe characters are aligned in horizontal rows as shown. It should appearobvious to one skilled in the art however, that the invention is notlimited to a single character font, and the strips of character patterns111-115 mounted on carrier means 1, or the character patterns that maybe etched on the surface of carrier means 1, may comprise a plurality offonts. In addition, although five columns or strips 111-115 are shown,it is clear that the number of columns of character patterns shown inFIG. 1 are for the sole purpose of illustration of the present inventionand hence should not be considered as limited to an arbitrary number ofcolumns. However, it should be understood that in the preferredembodiment of the present invention, between five and nine columns ofcharacter patterns are to be mounted on carrier means 1. The characterpatterns of the character font may be selected as opaque patterns on atranslucent medium or translucent stencilled patterns on an opaquemedium, depending upon the choice of application of the apparatus of thepresent invention which will be subsequently described. In either event,carrier means 1 should be capable of modulating radiant energy passingtherethrough.

As aforesaid, carrier means 1 is adapted to be rotated. For this purposea motor 15 is mechanically coupled to carrier means 1 by shaft 16. Motor15 should be capable of continuous, steady-state operation so thatcarrier means 1 rotates at a constant velocity. Motor 15 may be an ac ord.c. electric motor. In the preferred embodiment, motor 15 rotatescarrier means 1 at between and 300 revolutions per second. It is notedthat shaft 16 is not the exclusive mechanical coupling devicecontemplated, and may be replaced by a pulley system, frictional disk,or other mechanical coupling means.

The source of radiant energy 13 may comprise a plurality of conventionallight emissive elements 131-135. In the embodiment illustrated in FIG.1, each light emissive element 131-135 of the source of radiant energy13 is physically aligned with a single column or strip of characterpatterns 111-115 and is disposed in the interior of the carrier means 1along the central axis thereof so as to transmit radiant energyemanating therefrom through the character patterns mounted on thecarrier means 1. Light emissive elements 131-135 are designed to producea burst of high intensity, short duration radiation when energized sothat when the image formed by such radiation after the modulationthereof by a given character pattern is ultimately developed, the imageobtained will not be blurred and will exhibit high resolution. For thispurpose, each of the light emissive elements 131-135 may comprise agaseous discharge device such as a xenon flash tube, or an arc unitcomprised of arcing electrodes. Alternatively, light emissive elements131-135 may comprise conventional illumination lamps shielded bymechanical shutter means. The choice of light emissive elements 131-135forms no part of the present invention per se.

The source of radiant energy 13 is electrically connected to controlcircuitry 17 which acts to cause the selective energization of thevarious light emissive elements 131-135 therein. Control circuitry 17may comprise conventional counting and logic gating circuitry tosynchronize the flashing of light emissive elements 131-135 to therotation of carrier means 1. Such circuitry may be entirely conventionaland generally the exact nature of the circuitry employed will be afunction of the apparatus supplying data to the printing apparatus ofthe present invention. In addition to synchronization, control circuitry17 functions to actuate a selected light emissive element 131-135 when adesired character pattern in the column 111-115 associated with thatelement rotates into the proper position. Control circuitry 17 may, inturn, be controlled by peripheral data signal generators such as atypewriter keyboard, not shown, or punched cards containing datainformation, information recorded on paper or magnetic tape, or directlyby the output of a digital computer. Thus, it will be seen, that theprinting apparatus of the present invention has great flexibility withregard to the apparatus from which it may receive data signals and mayprint data that has previously been generated and stored, or data thatis concurrently produced. If the latter application is desired, controlcircuitry 17 may include still further circuitry that is well known inthe prior art to allow for backspacing, corrections, and/or otherconvenient functions.

Optical tunnel positioning means 7 includes lens 14 and two parallelplanar reflecting surfaces 18 and 19. The planes defined by surfaces 18and 19 are perpendicular to the axis of rotation of carrier means 1illustrated in FIG. 1. Lens 14 is disposed at the input end of theparallel reflecting surfaces 18 and 19, and the optical axis thereof islongitudinally disposed intermediate the two surfaces. Reflectingsurfaces 18 and 19 may be conventional planar mirrors each having alongitudinal dimension equal to the focal length of lens 14 so as topermit multiple reflections of radiant energy focused thereon by lens Mand each having width equal to at least the height of a characterpattern. The components of optical tunnel positioning means 7 aredisposed such that radiant energy transmitted to the surface of lens 14over any of a plurality of optical paths may be refracted by lens 14onto either planar reflecting surface 18 or 19, depending upon the angleof incidence of the radiant energy passing through lens 14, andreflected by surfaces 18 and 19 onto a single, predetermined areapositioned at the focal plane of lens 14, hereinafter referred to as theimaging position. The precise dimensions of the components of theoptical tunnel positioning means are determined by the known opticalprinciples used to design optical tunnels.

The operation of 'th e imaging portion of the printing apparatusillustrated in FIG. 1, will now be described. Motor when energized willcouple its rotation to the carrier means 1 through the shaft 16. Theangular velocity of the carrier means as driven by the motor 15 may beconsidered to be at a constant velocity which may be of the order of 300revolutions per second. As carrier means 1 rotates, control circuitry 17tracks the characters carried on the surface of carrier means 1 in thewell known manner so that the location of each character is known at alltimes. As data signals are generated by peripheral data equipment (notshown herein) connected to the control circuitry 17, the controlcircuitry 17 synchronously actuates one of the light emissive elements131-135 when the character selected by the peripheral data equipmentrotates into the proper position. For purposes of the embodiment shownin FIG. '1, the requisite position of a character for the actuation ofone of the light emissive element:

131-135 is in a plane perpendicular to the direction of propagation ofradiant energy emitted by the light emissive elements 131-135 andcoincidental with the focal plane of lens 14. Thus, if the data signalsgenerated by the peripheral data equipment direct control circuits 17 toirradiate a character pattern corresponding to the capital letter B,"control circuitry 17 actuates light emissive element when carrier means1 rotates into the position shown in FIG. 1. The actuation of lightemissive element 135 results in the emanation of high intensity, shortduration radiation from the light emissive element 135 through thecharacter pattern B which has been rotated into a plane perpendicular tothe direction of propagation of radiation emitted by element 135. Theradiation emitted from the light emissive element 135 is thus modulatedby the character pattern corresponding to the letter B as it propagatesradially outward from carrier means 1. Similarly, if the peripheral dataequipment selects the letter B, control circuitry 17 actuates lightemissive element 134 to produce the emission of high intensity, shortduration radiation when carrier means 1 rotates into the position shownin FIG. 1. The radiation emitted by light emissive element 134 will bemodulated by the character pattern corresponding to the mirror image ofletter E as it propagates through the carrier means 1. The purpose forreversing the character pattern for the letter B is subsequentlyexplained. Control circuitry 17 actuates only one of the light emissiveelements 131-135 for each rotation of carrier means 1 so that modulatedradiation corresponding to one character pattern is propagated for eachrotation. Thus, if carrier means 1 rotates at 300 revolutions per secondmodulated radiation corresponding to 300 character patterns per secondis propagated. The duration of the radiation emitted by each element131-135 is extremely short in comparison to the velocity of carriermeans 1 so that the imaged radiation corresponding to the selectedcharacter patterns that are ultimately received and developed will besharply defined, high resolution images.

The modulated radiation propagated radially outward from the surface ofcarrier means 1 will traverse an optical path, as indicated in FIG. 1,calculated to cause such radiation to impinge upon the surface of lens14 of optical tunnel positioning means 7. However, as is readilyapparent from FIG. 1, the radiation emitted from each light emissiveelements 131-135 will not traverse the same optical path. Thus, sincethe relame positions of the light emissive elements 131-135 with respectto the lens 14 are fixed, radiant energy will propagate towards lens 14over one offive independent paths for the embodiment shown, which fiveindependent paths are associated with the light emissive elements131-135. Depending upon the angle of incidence of impingent radiation,lens 14 may refract such radiation toward either reflecting surface 18or reflecting surface 19. It is, of course, understood that forimpinging radiation that is normal to lens 14, no refraction occurs. Inany event, radiant energy received by lens 14, irrespective of itssource, will emerge from optical tunnel positioning means 7 at preciselythe same location viz., the imaging position. For example, radiationemitted from light emissive element 1.35 will propagate through column115 and be refracted by lens 14 onto reflecting surface 19. Reflectingsurface 19 will reflect this radiation onto reflecting surface 18 fromwhich it will be reflected onto the imaging position. Similarly,radiation emitted from light emissive element 131 will propagate throughcolumn 111 and be refracted by lens 14 onto reflecting surface 18.Reflecting surface 18 will reflect this radiation onto reflectingsurface 19 from which it will be reflected onto the imaging position.However, radiation emitted from light emissive elements 134 and 132 willpropagate through columns 114 and 112 respectively, and be refracted bylens 14 onto reflecting surfaces 19 and 18 respectively, from whichreflecting surfaces the radiation will be reflected onto the imagingposition. Radiation emitted from light emissive element 133 willpropagate through column 113 in a plane perpendicular to the focal planeof lens 14 so that it will be transmitted directly to the imagingposition. In view of the foregoing, it may now be observed thatradiation emitted from one of light emissive elements 131435 will besubject to a number of reflections equal to the relative lateralposition of the light emissive element with respect to the optical axisof lens 14. In other words, a light emissive element that is twopositions removed from the optical axis emits radiation that isreflected twice; a light emissive element that is one position removedfrom the optical axis emits radiation that is reflected once; and alight emissive element that is on the optical axis emits radiation thatis not reflected. It is noted that those character patterns throughwhich radiation subject to an odd number of reflections is propagatedare represented by their mirror images so that the images of allcharacter patterns communicated to the imaging position will appear inthe proper perspective. Thus it is seen, that as carrier means 1rotates, modulated radiation is applied to the various input paths ofthe lens 14 by the selective actuation of light emissive elements131-135 of radiant energy source 13 by control circuitry 17, and theoptical tunnel means 7 positions such radiation so that it exits at asingle output location thereof. Consequently, the prior art requirementof laterally displacing carrier means 1, radiant energy source 13 orlens 14 is obviated.

The present invention as a whole, an embodiment of which is illustratedin FIG. 2, will now be described. The printing apparatus shown in FIG. 2comprises an imaging portion, as was described in detail in conjunctionwith FIG. 1, photoreceptor means 20, developing means 27 and transfermeans 32. Photoreceptor means 20 may take the form of anelectrophotographic plate comprising a photoconductive insulating body21 overlying a conductive backing member 22. The photoconductiveinsulating body 21 is adapted, in the well known manner, to have anelectrostatic charge applied to its surface and to selectively dissipatesuch electrostatic charge upon the exposure thereof to modulatedradiation corresponding to a light and dark pattern, such as a characterpattern, whereupon a latent image of such pattern is formed. Theelectrophotographic plate 20 may comprise, for example, a layer ofselenium overlying conductive backing member 22. In the illustrativeembodiment of FIG. 2, electrophotographic plate 20 is an an endless beltwhich is deployed around drive rollers 23 and 24. The endless beltelectrophotographic plate 20 has a width equal to at least the largestcharacter in the character pattern array carried by carrier means 1.However, as will be apparent to those of ordinary skill in the art, theelectrophotographic plate 20 is not limited to the endless beltconfiguration shown in FIG. 2, but may take any convenient form such asa drum or web. The conductive backing member 22 may be placed at groundpotential by applying ground to drive roller 23 which is in directcontact therewith. In the endless belt configuration illustrated in FIG.2, electrophotographic plate 20 is translated in the direction indicatedby arrow A by the drive rollers 23 and 24. Electrophotographic plate 20is adapted to be translated to a cleaning station 31, for a purposesubsequently described, and to charging unit 26. Cleaning station 31 maybe of the type described in U.S. Pat. No. 2,751,616 issued to M.I.Turner, Jr., et al. The electrostatic charge applied to the surface ofelectrophotographic plate 20 may be deposited thereon by charging unit26 which is electrically connected to a high voltage source 25. chargingunit 26 may comprise a corona discharge device of the type described inU.S. Pat. No. 2,777,957 issued to LE. Walkup.

Developing means 27 may comprise any well known form ofelectrophotographic developing apparatus which acts to develop anelectrostatic latent image by the application of electroscopic materialcapable of adhering to the electrostatic charge pattern on areelectrophotographic plate. The nature and composition of electroscopicmaterial is well known in the art as is the manner in which anelectrostatic latent image is treated with such material. A morecomplete description thereof may be found in U.S. Pat. No. 2,885,955issued to R.G. Vyverberg. It is noted that developing means 27 mayinclude means, if desired, whereby the polarity of an electrostaticlatent image may be changed so that the image may be directly developedto form an electrophotographic print corresponding to a photographicreversal of the original exposure. Such means is well known anddescribed in U.S. Pat. No. 2,817,765 issued to R.E. Hayford et al.

Transfer means 32 comprises a print receiving sur' face 28 shown in adrum configuration and positioned so that a surface portion thereof iscontiguous with a portion of electrophotographic plate 20. Printreceiving surface 28 may be paper, glass, plastic or any surface uponwhich it is desired to print characters. Developed images aretransferred print receiving surface 28 from electrophotographic plate 20in a well known manner. A charging device, such as corona dischargedevice 30, may deposit a charge on the back of print receiving surface28 which is of the same polarity as the charge on electrophotographicplate and is also opposite in polarity to the charge on theelectroscopic material utilized in developing the electrostatic latentimage. The charge on print receiving surface 28 removes theelectroscopic material from electrophotographic plate 20 and onto printreceiving surface 28 in the well known manner. Transfer means 32 mayalternatively comprise a print receiving surface 28 that is adhesive tothe electroscopic material. Once the electroscopic material istransferred to print receiving surface 28, it may be fixed by passingprint receiving surface 28 through a heating chamber not shown, wherebythe electroscopic material is fused to the surface 28. Although theprint receiving surface 28 is illustrated in a drum configuration, itshould be clearly un derstood that the drum does not close upon itselfand a gap exists between the end portions of print receiving surface 28as illustrated in FIG. 2. The purpose of this gap will be subsequentlyexplained.

In the operation of the printing apparatus illustrated in FIG. 2 thedrive rollers 23 and 24 translate electrophotographic plate 20 in thedirection indicated by arrow A in a well known manner. Aselectrophotographic plate 20 passes beneath charging unit 26, a uniformelectrostatic charge is deposited on photoconductive insulating body 21.The charged electrophotographic plate 20 is translated to a locationfacing the output of optical tunnel means 7 as shown in FIG. 2. At thislocation, electrophotographic plate 20 coincides with the focal plane oflens 14- or the imaging position of optical tunnel means 7 and isexposed to the modulated radiation imaged thereat by optical tunnelmeans 7 in the manner described above with respect to the imagingportion of the present invention described in conjunction with FIG. 1.Exposure of the charged plate 20 selectively dissipates the chargethereon in accordance with the modulated radiation corresponding to thelight and dark portions of the character pattern resulting in anelectrostatic latent image of the character pattern through which theradiant energy was transmitted. If the character pattern carried bycarrier means 1 is in the form of an opaque character on a translucentbackground, the charge remaining on plate 20 after exposure will be apositive latent image of the character pattern. If, however, thecharacter pattern carried by carrier means I is stencilled i.e., atransparent image on an opaque background, the charge on plate 20 willbe a negative latent image of the character pattern. It is understoodthat the terms positive and negative are here used in their photographicsense. It

is noted that the translation of electrophotographic plate 20 in thedirection of arrow A, which is perpendicular to the planes defined byreflecting surfaces 18 and 19, may be continuous or step-wise. In eithercase, the distance translated intermittent each discrete energization ofone of the light emissive elements 131435 is equal to the width of onecharacter pattern so that the electrostatic latent images onelectrophotographic plate 20 will be properly spaced with respect toeach other. If, however, the translation of electrophotographic plate 20is stepped, spaces may be skipped for indentations, tabulation, and endsof lines. Thus, electrostatic latent images of the desired characterpatterns carried by carrier means 1 are serially recorded onelectrophotographic plate 20.

When electrophotographic plate 20 is translated to the developing means27, the electrostatic latent images are developed to form visible imagesby well known treatment with electroscopic material. As aforesaid,developing means 27 may include additional means to reverse the imagesdeveloped thereby. Thus, a negative electrostatic latent image may bedeveloped to form a positive visible image or the converse relationshipmay be achieved. The developed image is transferred to print receivingsurface 28 when electrophotographic plate 20 reaches transfer means 32.

Print receiving surface 23, in drum configuration rotates in thedirection indicated by arrow B, whereby it is tangentially contiguouswith the surface of the plate 20. The electroscopic material is thentransferred to print receiving surface 28 by electrostatic transfer,adhesive transfer, or other conventional electrophotographic transfertechniques. It should be noted that although electroscopic materialtransfer has here been disclosed in conjunction with the preferredembodiment of the present invention, the electrostatic latent image mayalternatively be transferred directly to print receiving surface 28 fromelectrophotographic plate 20 without the intermediate step of developingthe image. If the electrostatic latent image is transferred directly itis developed on print receiving surface 28 by well known techniquessimilar to those with which the latent image on electrophotographicplate 20 is developed. The rotation of print receiving surface 28 issynchronized with the translation of electrophotographic plate 20; andduring one rotation of said print receiving surface 28, a line ofcharacters recorded on electrophotographic plate 20 is transferred toprint receiving surface 28. Print receiving surface 28 is advanced byadditional means, not shown, in a direction parallel to its axis ofrotation for a distance equal to the height of a line of printedcharacters when the gap between the end portions thereof rotates intothe vicinity of electrophotographic plate 20. This permits a new line ofcharacters to be recorded on print receiving surface 28 in theaforedescribed manner. Thus, it is readily apparent, that the images ofthe characters serially recorded on electrophotographic plate 20 in lineconfiguration are transferred to print receiving surface 28 in pageconfiguration. The gap between the end portions of print receivingsurface 28 permits the surface to be advanced as aforesaid withoutinterfering with electrophotographic plate 20. After transfer of theimage from electrophotographic plate 20 to print receiving surface 28,plate 20 is translated to cleaning station 31, where any electroscopicmaterial adhering to plate 20 is removed and electrophotographic plate20 is prepared for re-use in a well known and conventional manner asdescribed in US. Pat. No. 2,751,616. Thus, electrophotographic plate 20may be of length equal to one line of printed characters whereby thecycle of electrically charging the plate, exposing it to radiant energy,developing the latent image, transfering the image to print receivingsurface 28 and cleaning the plate is repeated for each line recorded; orelectrophotographic plate 20 may be of any desired length thatsatisfactorily carries out the above mentioned operations.

Although one application of the present invention has been describedwith reference to the specific embodiment illustrated in FIG. 2, it isnot strictly limited thereto. For example, the width ofelectrophotographic plate 20 may be greater than the height of onecharacter pattern. In fact, the width of. the electrophotographic plate20 may be equal to the width of print receiving surface 28. In thiscase, an entire line of developed images may be transferredsimultaneously to print receiving surface 28. Thus, an entire page maybe printed for each rotation of print receiving surface 28. To implementthis printing technique, carrier means 1 may be positioned such that itscentral axis of rotation is perpendicular to the plane of the drawing ofFIG. 2. In addition, a scanning optical means such as a conventionalrotating or traveling mirror may be located at the imaging position ofoptical tunnel means 7 so that the modulated radiation positionedthereon is scanned across the width of electrophotographic plate 20thereby depositing a line of latent images of characters onelectrophotographic plate 20. Accordingly, the individual characters areserially recorded to form parallel lines of latent images. Afterdeveloping in developing means 27, each line of character is transferredto print receiving surface 28 as aforesaid. Since an entire page isprinted for each rotation of print receiving surface 28, print receivingsurface 28 need not be advanced in a direction parallel to its axis ofrotation subsequent to each rotation thereof.

It should be apparent to those of ordinary skill in the art that theinstant invention admits of a plurality of alterations and modificationswhich in no way change the basic teachings thereof. For instance, theimaging portion of the present invention may be modified by positioningradiant energy source 13 externally of the carrier means 1 shown inFIG. 1. In this position, radiant energy may be propagated toward thecharacter patterns carried by carrier means 1 and reflected therefrominto the optical path defined by the optical tunnel means 7. Inaddition, loops may be formed in various positions along the length ofbelt 20 to compensate, if necessary, for intermittent and continuousmotion, or for any of the purpose.

While the invention has been particularly shown and described withreference to a specific embodiment thereof, it will be obvious to thoseskilled in the art that the foregoing and various other changes andmodifications in form and details may be made without departing from thespirit and scope of the invention. It is, therefore, intended that theappended claims be interpreted as including all such changes andmodifications.

What is claimed is:

1. Apparatus for printing desired character patterns on a surfacecomprising:

a plurality of selectively energizable radiation emissive elementsadapted to emit radiation of high intensity and short duration,

means for modulating the radiant energy emitted by said radiationemissive elements, said means for modulating including a plurality ofcharacter patterns associated with each ofsaid plurality of saidselectively energizable radiation emissive elements, each of saidplurality of character pattern means being rotatably positionable in anoptical path associated with a radiation emissive element;

at least two parallel planar reflecting surfaces disposed in a spacedapart relationship, said at least two parallel planar reflectingsurfaces defining a plurality of multiple reflection light pathstherebetween;

lens means including a plurality of radiation receiv ing pathsinterposed between said means for modulating and said at leat twoparallel planar reflecting surfaces, each of said plurality of radiationreceiving paths being in light communication with one of said pluralityof selectively energizable radiation emissive elements and acorresponding one of said plurality of multiple reflection light paths;

a movable belt of photoconductive insulating means having a width equalto at least the height of the largest of said character patterns anddisposed in tangential relationship with the focal plane of said lensmeans, said belt adapted to have a charge deposited thereon, and to havesaid charge dissipated by said modulated radiant energy communicated tosaid belt from said at least two parallel planar reflecting surfaces toform electrostatic latent images of said character patterns;

means for developing said electrostatic latent images;

means for transferring said developed images from said belt to a surfaceoperably positioned contiguous to a portion of said belt;

means for rotating said surface about an axis perpendicular to thelongitudinal dimension of said belt, and

means for advancing said surface in a direction parallel to its axis ofrotation subsequent to each rotation thereof.

2. Apparatus for printing desired character patterns on a surface inaccordance with claim 1 wherein said means for modulating comprises:

rotatable drum means having thereon a plurality of columns of characterpatterns, each of said columns including one of said associatedplurality of character patterns and adapted to interpose one of saidcharacter patterns in said associated optical path due to the rotationof said drum means; and

means for selectively energizing said plurality of selectivelyenergizable radiation emissive elements in synchronization with therotation of said drum means when a desired character pattern in one ofsaid plurality of columns of character patterns is rotatably positionedin the optical path associated therewith.

3. Apparatus for printing desired character patterns on a surface inaccordance with claim 2 wherein said lens means and said planarreflecting surfaces are disposed in optical tunnel configuration forpositioning at the focal plane of said lens means radiation received atsaid plurality of radiation receiving paths.

4. Apparatus for printing desired character patterns on a surface inaccordance with claim 3 wherein said plurality of selectivelyenergizable radiation emissive elements is positioned interiorly of saiddrum means; and said means for selectively energizing said plurality ofselectively energizable radiation emissive elements comprises means toenergize one of said plurality of radiation emissive elements duringeach rotation of said drum means.

f5. Apparatus for printing desired character patterns on a surface inaccordance with claim 4 wherein said developing means comprises meansfor applying electroscopic material to said electrostatic latent images.

1. Apparatus for printing desired character patterns on a surfacecomprising: a plurality of selectively energizable radiation emissiveelements adapted to emit radiation of high intensity and short duration,means for modulating the radiant energy emitted by said radiationemissive elements, said means for modulating including a plurality ofcharacter patterns associated with each of said plurality of saidselectively energizable radiation emissive elements, each of saidplurality of character pattern means being rotatably positionable in anoptical path associated with a radiation emissive element; at least twoparallel planar reflecting surfaces disposed in a spaced apartrelationship, said at least two parallel planar reflecting surfacesdefining a plurality of multiple reflection light paths therebetween;lens means including a plurality of radiation receiving paths interposedbetween said means for modulating and said at least two parallel planarreflecting surfaces, each of said plurality of radiation receiving pathsbeing in light communication with one of said plurality of selectivelyenergizable radiation emissive elements and a corresponding one of saidplurality of multiple reflection light paths; a movable belt ofphotoconductive insulating means having a width equal to at least theheight of the largest of said character patterns and disposed intangential relationship with the focal plane of said lens means, saidbelt adapted to have a charge deposited thereon, and to have said chargedissipated by said modulated radiant energy communicated to said beltfrom said at least two parallel planar reflecting surfaces to formelectrostatic latent images of said character patterns; means fordeveloping said electrostatic latent images; means for transferring saiddeveloped images from said belt to a surface operably positionedcontiguous to a portion of said belt; means for rotating said surfaceabout an axis perpendicular to the longitudinal dimension of said belt,and means for advancing said surface in a direction parallel to its axisof rotation subsequent to each rotation thereof.
 2. Apparatus forprinting desired character patterns on a surface in accordance withclaim 1 wherein said means for modulating comprises: rotatable drummeans having thereon a plurality of columns of character patterns, eachof said columns including one of said associated plurality of characterpatterns and adapted to interpose one of said character patterns in saidassociated optical path due to the rotation of said drum means; andmeans for selectively energizing said plurality of selectivelyenergizable radiation emissive elements in synchronization with therotation of said drum means when a desired character pattern in one ofsaid plurality of columns of character patterns is rotatably positionedin the optical path associated therewith.
 3. Apparatus for printingdesired character patterns on a surface in accordance with claim 2wherein said lens means and said planar reflecting surfaces are disposedin optical tunnel configuration for positioning at the focal plane ofsaid lens means radiation received at said plurality of radiationreceiving paths.
 4. Apparatus for printing desired character patterns ona surface in accordance with claim 3 wherein said plurality ofselectively energizable radiation emissive elements is positionedinteriorly of said drum means; and said means for selectively energizingsaid plurality of selectively energizable radiation emissive elementscomprises means to energize one of said plurality of radiation emissiveelements during each rotation of said drum means.
 5. Apparatus forprinting desired character patterns on a surface in accordance withclaim 4 wherein said developing means comprises means for applyingelectroscopic material to said electrostatic latent images.